Human neutrophils and monocytes are attracted to sites of inflammation, engulf microorganisms and secrete granule contents and toxic oxygen products. The purpose of this project is to define the biochemical structure and function of surface receptors, transduction proteins and effector systems involved in phagocyte responses to inflammation. Studies focus upon: (i) the receptor for bacterially derived formyl peptides, the formyl peptide chemotactic receptor (FPCR); (ii) pertussis toxin inhibitable GTP binding regulatory proteins (Gi) in myeloid cells required for FPCR and other receptor mediated cellular responses; (iii) cytosolic transducer proteins and the membrane cytochrome b558 (CYTO b) mediating superoxide production; (iv) cytoskeleton effector proteins involved in secretion. We show that both FPCR and Gi are present and functionally coupled in an intracellular pool in neutrophils. About 30% of neutrophil Gi is intracellular and this pool contains a higher ratio of Gi3 relative to Gi2 than that seen in plasma membrane. Using an antibody we developed to the C- terminus of the large subunit of CYTO b, we showed that CYTO b large subunit is transmembrane, that the C-terminus is cytoplasmic and plays an important functional role in superoxide production, and that >90% of CYTO b is intracellular in resting neutrophils and translocated to the surface with activation. We show that a 47 kDa and 65 kDa cytoplasmic proteins are essential for the transduction events in neutrophils leading to superoxide production and are defective in chronic granulomatous disease. Glycosylation of CYTO b differs in neutrophils and eosinophils. We find that the cytoskeletal protein, fodrin, is the major calmodulin binding protein in neutrophils.